The present invention relates to an optical scanner device and an image forming apparatus.
In the image forming apparatus, the optical scanner device is installed. The optical scanner device is structured so as to store a rotational polygonal mirror (hereinafter referred to as a polygonal mirror) for reflecting and polarizing a light beam from a light source and optical elements such as an image forming lens for focusing the light beam polarized by the polygonal mirror on the surface of a photosensitive drum in an almost closed housing. In the housing for storing such optical elements, if the position relationship of the optical elements is shifted, a defective image is formed in the process of image formation. Therefore, the optical elements are fixed at predetermined positions of the housing with high precision of position.
However, the housing receives vibration due to driving of the image forming apparatus and vibration due to rotation of the polygonal mirror rotating at super-high speed. Further, noise is produced by the super-high speed rotation of the polygonal mirror. Therefore, it is required for the housing to reduce the vibration and noise inasmuch as is possible.
Conventionally, for example, as an example of increasing the rigidity and strength of the housing of the optical scanner device and suppressing vibration and deformation of the housing, there is a double-wall structure having an inner wall formed along an outer wall of the housing available.
The housing disclosed in Japanese Patent Application 2004-125920 is composed of a double-wall structure, in which between the outer wall and the inner wall, a rib perpendicular to the outer wall and inner wall is installed. However, in the housing of the structure described in Japanese Patent Application 2004-125920, a harness is installed between the outer wall and the inner wall, so that a sufficiently high rib cannot be used. Therefore, sufficient rigidity cannot be obtained and vibration and deformation of the housing cannot be suppressed sufficiently. Further, as the printing of the image forming apparatus is speeded up, the rotation of the polygonal mirror is also speeded up, so that a problem arises that the noise is increased due to it.